In the world of particle physics, every discovery -or lack thereof- can make waves. Recently, the CMS collaboration has published the first diboson paper in the Physics Letters B journal using the LHC Run 3 data, specifically the production of WW boson pairs, at a center-of-mass energy of 13.6 TeV. While the paper provides valuable insights into these interactions, there is one key takeaway: no new physics was discovered, and the Standard Model (SM) of particle physics continues to hold strong.
Diboson production refers to processes where two vector bosons, like W bosons, are produced in high-energy particle collisions. These interactions are of immense interest to physicists because they can provide crucial tests of the SM, which describes the fundamental forces and particles of our universe. In particular, the WW boson pair production process involves the creation of two W bosons, which are responsible for mediating the weak nuclear force. This type of production is relatively rare and highly energetic, making it a prime candidate for investigation at the LHC, where particles are smashed together at extremely high energies. The new results from the CMS experiment offer deeper insights into the behavior of these interactions at 13.6 TeV, a moderate increase in energy from previous runs.
The analysis was performed by looking at proton-proton collisions with a total energy of 13.6 TeV and included the data collected by the CMS detector in 2022. The figure shows all the events that pass the signal selection, as a function of how many jets they have. One can immediately see that the majority of events have zero jets. The measured data are represented by the black circles. The different processes are shown in coloured histograms and should account for the measured data points. This is true, as can be seen in the lower part of the figure, which shows that the data over SM ratio is compatible with unity for all the bins. Out of the processes represented, we are interested in the light blue one, the WW production. The magnitude of this process is left free in a fit that tries to find the best agreement between the data points and the sum of all histograms. The result of the fit is also shown in the figure. The measured inclusive cross section is 125.7 +/- 5.6 pb, which is consistent with the theoretical prediction of 128 +/- 3 pb.
The original analysis was first presented at the end of March 2024 at the Moriond Conferences and it has been one of the fastest publication processes. While the big collaborations at the LHC are struggling with getting papers published quickly in the last years, our group has managed to make an exception for this interesting study.
